The present invention relates to an excessive descent-rate warning system particularly useful for helicopters.
At the present time, helicopters are usually not equipped with a warning system which automatically warns the pilot in the event the rate of descent of the helicopter is excessive. Accordingly, the helicopter pilot, or co-pilot, is usually required to continuously monitor the instruments and to continuously make mental judgements as to whether the rate of descent is excessive for any particular situation. This not only increases the workload on the pilot, but also increases the possibility of an accident because of insufficient alertness or mistake in judgement.
A number of excessive descent-rate warning systems have been developed for use in conventional fixed-wing aircraft. Examples of such systems are described in U.S. Pat. Nos. 4,060,793, 3,958,218, 3,946,358 and 3,715,718. Such systems, however, being designed for fixed-wing aircraft which land at a relatively high forward speed when compared to helicopters, are generally not applicable to, or used in, helicopters. A number of warning systems for helicopters have been proposed (e.g. U.S. Pat. No. 3,979,717), but these are usually attitude responsive, to warn of a possible tail contact upon landing.